Rapid response activation (RRA), triggered chiefly by surpassing threshold vital sign abnormalities (TVSAs), is designed to intervene at the earliest point in a patient's deteriorating course. The authors aimed to quantify the incidence of TVSA among patients hospitalized on acute care units in a hospital that uses rapid response. During the course of 6 months, the authors compared adverse events (mortality, unexpected intensive care unit [ICU] transfers, and cardiopulmonary arrest) and TVSA among patients who triggered an RRA, patients with TVSAs and no RRA, and all other patients. At least 1 TVSA was recorded in 31.9% of stays and 12.2% of patient-days. RRA patients were more likely (22.5%) than other TVSA patients (7.9%) and other patients (1.8%) to have an adverse event (P < .01). Incidence varied by vital sign. During the investigation, only 2.5% of TVSA opportunities triggered an RRA. As systems engage electronic workflows, automatically triggering RRAs based solely on TVSAs could place a tremendous burden on systems.